Heavy Duty Trucking

NOV 2014

The Fleet Business Authority

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90 HDT • NOVEMBER 2014 www.truckinginfo.com I s there an established time or mile- age for replacing air bags on air suspensions?" Kevin Tomlinson, maintenance manager at South Shore Transportation in Sandusky, Ohio, posed that question as a panelist during an industry meeting in September. The format of the session, which focused on decision-making, did not allow for an answer — but it's a good question. Because trucks, tractors and trailers operate in a wide range of load and operating conditions, there seems to be no predictable life for air springs, shock absorbers, height and pressure valves, bushings, fasteners and the many other parts of an air-ride suspension. Tom- linson, who's also first vice chairman of the Technology & Maintenance Coun- cil of American Trucking Associations, understands that, and also that the ses- sion, during TMC's Fall Meeting, was not designed to get him any answers. One day last month he reported that he had a dry-bulk tanker in the shop to change out its air bags, and discussed the subject. "We've had vehicles that have run a million miles with the original bags, others that went 400,000," he said. "You never know. This trailer hauls out of a limestone quarry just a few miles down the turnpike and back to a shin- gle plant right in town. A round trip is maybe 30 miles, and it'll make five springs as they travel at high speeds. Regular inspections combined with record-keeping will track wear and dic- tate when a bag, or a set of them, need to be replaced. Vehicles in the same kind of service in the same areas might establish a pattern that could suggest a change-out time for all of them, or might not. TMC's Recommended Practice 643, Air-Ride Suspension Maintenance Guidelines, said air bags should be inspected every 50,000 miles, but that might be too long for trips a day. It spends more time loading and unloading than running, so doesn't get many miles. On something like that, miles don't mean much." Exposure to ozone in the atmosphere and the sun's ultraviolet rays can age air bags' rubber, but that doesn't show up as it does in old tires, Tomlinson said. Much more important are wear and tear from road conditions as the bags compress and stretch over high and low points in pavement, trail or uneven off-road terrain, and debris slung at the Change Air Springs? Type of service and wear, along with road damage, tend to establish any schedule, if that's possible. Is There a Set Time to This 14-year-old Heil pneu- matic tanker owned by South Shore Transportation in Ohio runs only about 150 miles a day, and its air springs finally needed replacement last month. All four bags were changed out. Tom Berg • Senior Editor PHOTOS: SOUTH SHORE TRANSPORTATION

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